AP Environmental Science Unit 1 Cheatsheet: The Living World: Ecosystems

Predation: Predator eats prey. Relationship drives population cycles.

Symbiosis (close, long-term interaction):

• Mutualism: Both species benefit
• Commensalism: One benefits, one unaffected
• Parasitism: One benefits, one harmed

Competition: Occurs within or between species when resources are limited.

Resource Partitioning: Species use resources differently (by place, time, or method) to reduce competition impact on survival.

Definition: Movement of phosphorus atoms/molecules between sources and sinks.

Major reservoirs: Rock and ocean sediments (phosphorus-bearing minerals).

No significant atmospheric component.

Why scarce: Rocks weather slowly → phosphorus availability is limited.

Limiting nutrient: Often limits primary production in freshwater and some terrestrial ecosystems.

Biological role: Absorbed by plant roots → incorporated into DNA, RNA, ATP → consumed by animals.

Hydrologic cycle: Sun-powered movement of water (solid, liquid, gas) between sources and sinks.

Primary reservoirs: Oceans (largest), ice caps, groundwater.

Primary Productivity: Rate solar energy converts to organic compounds via photosynthesis (energy/area/time).

Gross Primary Productivity (GPP): Total photosynthesis rate.

Net Primary Productivity (NPP): Energy stored after respiration losses (GPP − respiration).

Units: kcal/m²/yr (or similar energy/area/time).

Light penetration in water: red wavelengths are absorbed rapidly within the first few meters, while blue/green light penetrates deepest (>100 m in very clear water) → limits photosynthesis to the shallow photic zone.